1. Field of the Invention
This invention is in the field of slice lip adjusting devices wherein disengagement or disorientation between the slice lip and the adjusting arm are prevented.
2. Description of the Prior Art
The prior art contains numerous examples of papermaking machines provides with means for controlling the slice opening to thereby vary the profile of the paper in the cross-machine direction with respect to basis weight, moisture, caliper and the like.
Beachler U.S. Pat. No. 3,014,527 describes a paper machine having a generally triangular shaped headbox wherein there is an inlet provided at one apex of the triangle and a stock outlet at another apex, together with pivot means at the third apex which permits an associated wall to move relative to another wall forming the triangular headbox. The device provides direct means for matching the flow rates of stock to the paper machine speed, stock character, and basis weight of the sheet to be formed on the machine by varying a plurality of adjustable throat dimensions in the inlet.
Beecher U.S. Pat. No. 3,413,192 is directed to a more sophisticated automatic type slice adjusting mechanism. The slot aperture at the slice is made variably adjustable along the length by adjusting mechanisms which are controlled directly or indirectly by servo-integrators each consisting of a servo-operational amplifier having its output connected to a servo-motor the shaft of which mounts a tachometer which feeds back information to the input of an amplifier which ultimately readjusts the slot opening.
U.S. Pat. No. 3,902,961 in which one of the present coinventors was a copatentee describes a papermaking machine having a slice lip construction for controlling the trajectory of stock emerging from the headbox slice by deflecting the stock stream downwardly against the forming wire and changing the deflection with change in size of slice opening to maintain an optimum slice strain angle relative to the wire.
In U.S. Pat. No. 3,167,470 there is described a paper machine headbox having an adjustable slice which is adjustable horizontally and vertically. The vertical adjustment is accomplished by changing the positioning of a plurality of clamp blocks while horizontal adjustment is accomplished by a pivotal mounting.
Mehlman et al U.S. Pat. No. 3,542,645 describes a papermaking machine with an adjustable slice lip utilizing screw adjusting mechanisms, each screw having two ratchet wheels which are adapted to be engaged by a pawl connected to an electrical solenoid, one solenoid operating to turn the screw in one direction and the other to turn it in the opposite direction.
U.S. Pat. No. 3,556,935 provides for an adjustable pressure nozzle with means for adjusting the convergence angles or vertical tapers in the nozzle approach channels.
U.S. Pat. No. 3,575,799 provides an adjustable slice opening which is achieved by providing a turnbuckle assembly including a threaded adjusting rod secured to the upper lip of the slice opening, and a turnbuckle sleeve member which threadedly engages the adjusting rod to move the adjusting rod vertically and thereby adjust the upper lip of the slice opening.
U.S. Pat. No. 3,703,436 describes a headbox in which the slice opening dimension is controlled in response to signals corresponding to the total head of fluid in the headbox, the rate of flow of the suspension into the headbox, and the speed of the forming wire which issues from the headbox slice. The slice opening is controlled in an anticipatory manner to compensate for the slow response of the total head in the headbox to changes occurring in response to slurry mass flow rate into and out of the headbox.
U.S. Pat. No. 3,738,910 describes a nozzle adjusting arrangement for a papermaking machine headbox. The structure includes a cylindrical bearing which is supported by a wall structure on the headbox for rotation about a horizontal axis. The upstream edge of the upper lip of the stock discharge nozzle is journaled in a socket defined in the outer periphery of the cylindrical bearing for supporting the upstream edge of the upper lip relative to the bearing. A linkage connected to the cylindrical bearing rotates the bearing about its central axis and moves the upper lip, the upstream and downstream edges thereof moving along paths each having a horizontal component.
Another adjustable slice lip is disclosed in U.S. Pat. No. 3,994,773. That patent, however, deals primarily with a means for measuring the vertical displacement of the upper slice lip as a result of signals generated by relative vertical movement between the upper and lower slice lips.
U.S. Pat. No. 3,976,539 describes an adjusting structure for the upper lip of a slice including a support structure which has an elongated substantially horizontal lower region situated adjacent an upper lip of the slice. An elongated strip extends along the lower region of the support structure and projects downwardly beyond the lower region where the strip terminates in an elongated substantially horizontal free edge which defines the upper lip of the slice. An elongated plate which is situated in front of and adjacent the front support structure provides structure for adjusting the strip.
Other patent disclosures dealing with adjustable slice structures will be found in U.S. Pat. Nos. 4,008,123; 4,089,739; 4,326,916; and 4,373,993.
The assignee of the present application markets a slice lip adjuster which is described in manual J006-10004, dated February 1978. This manual describes the headbox slice lip and slice lip adjusters which have become quite conventional in the field. The slice lip is adjusted by means of a series of adjusters spaced across the width of the slice body. The slice lip is held in position against the slice body with a spring-loaded adjusting arm. A spring presses a hook portion on the adjusting arm into a groove of the slice lip which forms a seat with the hook portion and keeps the lip in contact with the slice body. The spring-loaded adjusting arm allows for movement of the slice lip to a relatively small extent (0.015 inch or so).
It has been found in practice that because of the forces involved in moving the slice lip, the slice-adjusting arm compresses the spring, causing the arm to crawl out of the slice lip groove thereby rendering all arm measurements useless.